When it comes to plants, I'm pretty much a novice. I've kept Java Fern with some success in the past, and these days I'm doing very well with Amazon Swords (they seem to runner/bud/whatever you call it more often than I can keep track of, now). I've had smatterings of success with a few other plants that nobody seems to be able to kill.

Recently, I've acquired a very bright system of lights, with some 108W of power in two T5HO bulbs under a metallic, high-reflective, well, reflector. The doubling of the light (by measure of Watts per Gallon) looks more like trippling to my eyes, and I want to get into using my plants more productively than simply cloning my swords.

Particularly, I'm interested in learning how to calculate the photoperiod necessary, in hours. As it stands, the tank receives minimal daylight except on very sunny mornings in early spring and late fall (local), most of which is still ablated by the background and the hood. Right now, I use a photoperiod of (admittedly too much) 15 hours, running 12 hours from 10 AM to 10 PM, and then an additional three hours.

I know I should reduce this, but I tend to keep odd hours myself - perils of grunt-work, so I am often not awake until late in the morning, and if I set the photoperiod to precisely 12 hours, the lights would shut off shortly after I got home. I'd only have time to enjoy my tanks properly on my days off!

That all being said, how does one calculate the actual light requirements in lumens for a tank? I was going by WPG (giving me about 2 now), then I read that was deficient, then I was going by 12-on, 12-off for the light timings, and realized that nowhere in the world really gets twelve hours of daylight and twelve hours of night except during twice-annual astronomical events...

Can anyone help a moron learn his craft by suggesting a decent timing schedule? Preferably by explaining how they arrived at it, so that I can mimic it?

The tank is planted with a peculiar Rotala (it was sold as R spp, so I'm not sure which Rotala), the aforementioned Amazon Swords, and a smattering of Egeria densa.

Also: If I added a floating plant, that would probably be impossible to bypass as far as my plants light requirements went, right?_________________http://auditorandagentleman.blogspot.com - now with 100% more fish.
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